This section is intended to provide a background or context to the invention recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Mining shovels and other large industrial vehicles may have an upper frame configured to rotate relative to a lower frame via a swing gear assembly, such as to move a coupled work implement (e.g., a dipper shovel) to a particular location. Often, the swing gear assembly includes a swing gear (e.g., a swing rack) coupled to the lower frame, a series of rollers configured to facilitate rotation of the upper frame relative to the lower frame, and a thrust rail (i.e., a support rail) coupled to the swing gear. The thrust rail may be configured to interface with both the swing gear and the rollers, as well as to retain the rollers in a desired position. The swing gear may also include a machined inner surface intended to retain the thrust rail and the rollers.
During operation of the mining shovel (e.g., as the upper frame is rotated), the rollers may be subject to a pressure load due to the impact or weight of the upper frame, such that the rollers are pushed radially outward from the swing gear assembly. Due to the load, the rollers and the thrust rail may be biased in a radially outward direction, and the fasteners coupling the components of the swing gear assembly may be stretched or broken. Further, the thrust rail often extends above the inner surface of the swing gear, resulting in a bending moment on a top portion of the inner surface of the swing gear. The outward radial force of the rollers may thus cause wear to the rollers, the thrust rail, and/or the inner surface of the swing gear, which may reduce the efficiency or effectiveness of the mining shovel and may require replacement of a portion of the swing gear assembly.
Swing gear assemblies may include devices configured to impede the radial thrust of an associated roller circle. An example of such a device can be found in U.S. Patent Publication No. 2013/0287331, published Oct. 31, 2013, for “Thrust Roller Bearing,” which discloses a thrust cage for retaining a plurality of rollers. The thrust cage includes a plurality of separate cage bodies configured to retain the individual rollers in a roller accommodating space. However, the cage bodies do not include both a horizontal and a vertical surface configured to provide support, and the cage bodies may not inhibit a rotational movement of the rollers relative to an adjacent component.